Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/trigonometry/less-basic-trigonometry/pythagorean-identity/e/circles-and-pythagorean-identities?utm_source=YT&utm_medium=Desc&utm_campaign=Trigonometry Watch the next lesson: https://www.khanacademy.org/math/trigonometry/less-basic-trigonometry/pythagorean-identity/v/using-the-pythagorean-trig-identity?utm_source=YT&utm_medium=Desc&utm_campaign=Trigonometry Missed the previous lesson? https://www.khanacademy.org/math/trigonometry/less-basic-trigonometry/pythagorean-identity/v/pythagorean-trig-identity-from-soh-cah-toa?utm_source=YT&utm_medium=Desc&utm_campaign=Trigonometry Trigonometry on Khan Academy: Big, fancy word, right? Don’t be fooled. Looking at the prefix, tri-, you could probably assume that trigonometry (“trig” as it’s sometimes called) has something to do with triangles. You would be…